Reasonably-pure drinking water is an absolute necessity of life and clean, fresh-tasting drinking water is one of its pleasures. Most persons in well-developed countries like the United States have access to safe, reasonably-pure drinking water. But even in areas having water suitable for human consumption, such water may contain minerals, e.g., iron and calcium, and/or chemicals and other substances.
While such non-water constituents may not be harmful to humans, they often impart an unpleasant taste or odor to the water. And normally-high-quality drinking water sometimes contains bacteria or other microorganisms which may impart a bad taste to the water or otherwise impair its quality. Often, such an eventuality results from a temporary deficiency in the water treatment facility.
One well-known approach for removing impurities from drinking water is distillation. Distillation involves boiling water to form water vapor and then cooling such vapor to a temperature below the condensation temperature, i.e., below about 212.degree. F. The resulting liquid, sometimes referred to as condensate or distillate, is collected for drinking or the like. Distillation separates pure water from the entrained minerals and other potentially bad-tasting impurities. And quite aside from improving the sensory quality of water, the high temperatures involved in the process are sufficient to kill many types of potentially-harmful microorganisms.
Water distillers commonly use a heating coil to boil, as steam, the water from a raw water container. A fan blows air across condensing coils which cools the steam and condenses it back to now-purified water. The distiller electrical circuit usually has some type of thermostat to shut down the distiller when the water in the raw water container is exhausted or is nearly so.
U.S. Pat. No. 4,342,623 (Loeffler) and U.S. Pat. No. 4,861,435 (Sweet, Jr.) disclose control circuits for distillers. The circuit of the Loeffler patent uses a single thermostat in series with the incoming electrical line to shut off all functions of the distiller including the fan and heater coil. Such thermostat must be manually reset after tripping.
The apparatus disclosed in the Sweet, Jr. patent carries out what might be described as a continuous, rather than a batch, distilling process. Water is boiled in a boiling tank and transferred, in the form of steam, to a storage tank. When the storage tank is substantially full, a float switch signals that fact by shutting down that part of the apparatus used for distilling. As distilled water is consumed by the user, distilling resumes. And if the rate of consumption is at least equal to the rate of distillation, the distilling process is continuous.
The apparatus electrical circuit (which, in view of the invention, is relatively complex) includes a pressure switch, a float switch, two thermostats and a water solenoid. There is apparently no fan.
An improved water distiller control circuit which addresses problems and shortcomings of known control circuits would be an important advance in the art.